This is an investigation into the role of pulmonary mucociliary transport in the pathogenesis of chronic obstructive lung diseases, specifically cystic fibrosis, and asthma. The rate of tracheal mucociliary transport is measured by observing (through a fiberoptic bronchoscope) the movement of 1.Omm Teflon discs across the tracheal mucosa. The rate of movement of the discs reflects that of the mucus layer and is determined by measuring the change in image size of the Teflon discs on films taken through the bronchoscope. This technique will be used to study the rate of tracheal mucociliary transport in normal volunteers and patients with cystic fibrosis and asthma. Transport rates will be measured before and after the administration of drugs which we have found in our previous studies to stimulate or which may potentially stimulate mucociliary transport (beta adrenergic stimulators and phosphodiesterase inhibitors). The effect of aerosol and mist tent therapy on mucociliary transport rates will also be studied, in order to evaluate the efficacy of such therapy on pulmonary clearance mechanisms. Transport rates will be measured before and after exposure to aerosols of mucolytic agents or decongestants, as well as bland aerosols in acute (10-15 minute) and longer term (overnight) exposures. In patients with cystic fibrosis, mucosal biopsies will be taken immediately after measurement of mucociliary transport rates and processed for scanning and transmission electron microscopy in order to correlate tracheobronchial surface ultrastructure with function.